It is known that in the laying of cables of aerial electric lines, data distribution lines, railway lines or others, plants are used which realize the principle of “braked stretching”, whereby one or more “winch” machines recover one or more lines or old conductors to be substituted (re-conductoring) and one or more “brake” machines brake the new conductors during laying in order to guarantee a geometric configuration of the span which avoids interference with natural and/or artificial obstacles. In their turn, the laying machines comprise one or more combined pairs of capstans which drive the respective hydraulic pumps and the relevant hydraulic circuits, in order to be able to lay simultaneously one or more cables at a time.
Synchronization devices are also known for the “winch” or “brake” machines of the laying plants in order to carry out the operations of laying, stretching and/or substitution of electric cables, optic fibers, lines or similar.
An example of a known synchronizing device is described in the patent application No. WO2009/078044 in the name of the Applicant. This known synchronizing device comprises automatic adjustment means to adjust the recovery speed of each individual cable to the winch station, such as a position detector associated to each individual capstan of each individual winch or brake.
The adjustment means also comprise at least a control unit connected to each pair of capstans of each machine of the winch station; the control unit intervenes, in relation to the signals coming from the position detectors, on the members that command and adjust the rotation speed of the respective capstans of each machine. In this way it is possible to recover several cables substantially at the same speed, and to control the recovery speed of the cables of the traction/recovery members in an independent way, by means of the associated control unit, so as to avoid possible misalignments of the cables.
Each machine is controlled by means of a corresponding command user interface, such as for example an adjustment “joystick”, so that it is thus possible to modify, even dynamically during their functioning, the relative work or functional parameters.
One disadvantage of this synchronizing device is that, although it allows to carry out a substantially independent adjustment of the rotation speed of each pair of capstans to the winch station, as the number of cables which are simultaneously laid increases, so does the probability of generating possible imbalances in the laying configuration of the cables, depending on the different operating conditions under which the cables are laid.
Indeed the difference in performance of each laying circuit, such as for example the different efficiency of the individual pulleys installed on the towers, the different geometries of each catenary determined by angles or non-linear developments of the span of the cables, the different yields of the hydraulic control circuits to the brake machines can generate misalignments in the group of conductors, even though the heads are recovered at the same speed. Therefore one or more cables have a laying profile which differs with respect to that of a reference conductor.
This disadvantage is even greater when the conductors are laid following a traditional procedure in which, with a single pulling line at the winch side, several conductors are recovered by using a head-board or running board, which allows to connect a line to a multiple number of conductors. In this situation what we described before can easily happen, and that is, despite a uniform recovery speed to the winch machine, because it is associated to a single line, there are imbalances and misalignments of the conductor cables because of the different operating conditions of the individual spans and/or of the individual adjustment circuits to adjust the brake machines.
Other known synchronization devices of the circuits on the brake side are based on a partial mechanical connection of the same, with limitation of the torque that can be transmitted, the application of which allows to partially balance the differences in tension between conductors and adjacent circuits thanks to the connection between them. This solution is costly, however, in terms of mechanical production and is expensive to extend to multiple machines which are not physically connected to each other.
Other known synchronization devices of circuits on the brake side are based on a hydraulic or electric connection of the command members so that they can be operated with similar hydraulic or electric values for every circuit. Such devices do not however allow to compensate or correct differences in tension in the cables themselves, or geometric imbalances between them, because they do not guarantee the independent adjustment of each circuit.
Therefore the supervision and/or the adjustment of specific working or functional parameters which allow to determine a homogenous effect for each controlled laying circuit is not an easy operation for an operator working on the brake machine or machines. In particular, in order to keep the adjustment of each individual cable simultaneous, the operators must simultaneously control different user interfaces, one for each machine and each generally with multiple commands, and it is therefore difficult to maintain a desired alignment and synchronized execution as the number of cables laid increases.
One purpose of the present invention is to achieve a balancing and synchronizing device for machines for laying cables which allows to control the functioning of two or more cable laying machines on the brake side, adjusting the laying or drawing tension substantially simultaneously and independently for each individual circuit, minimizing possible positioning imbalances.
A further purpose of the present invention is to achieve a balancing and synchronizing device for cable laying machines on the brake side in which specific work parameters can be easily adjusted by a single operator irrespective of the number of circuits connected.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.